The libavdevice library provides the same interface as
libavformat. Namely, an input device is considered like a demuxer, and
an output device like a muxer, and the interface and generic device
options are the same provided by libavformat (see the ffmpeg-formats
manual).

In addition each input or output device may support so-called private
options, which are specific for that component.

Options may be set by specifying -optionvalue in the
FFmpeg tools, or by setting the value explicitly in the device
AVFormatContext options or using the libavutil/opt.h API
for programmatic use.

Input devices are configured elements in FFmpeg which enable accessing
the data coming from a multimedia device attached to your system.

When you configure your FFmpeg build, all the supported input devices
are enabled by default. You can list all available ones using the
configure option "–list-indevs".

You can disable all the input devices using the configure option
"–disable-indevs", and selectively enable an input device using the
option "–enable-indev=INDEV", or you can disable a particular
input device using the option "–disable-indev=INDEV".

The option "-devices" of the ff* tools will display the list of
supported input devices.

AVFoundation is the currently recommended framework by Apple for streamgrabbing on OSX >= 10.7 as well as on iOS.

The input filename has to be given in the following syntax:

-i "[[VIDEO]:[AUDIO]]"

The first entry selects the video input while the latter selects the audio input.
The stream has to be specified by the device name or the device index as shown by the device list.
Alternatively, the video and/or audio input device can be chosen by index using the
-video_device_index <INDEX>
and/or
-audio_device_index <INDEX>
, overriding any
device name or index given in the input filename.

All available devices can be enumerated by using -list_devices true, listing
all device names and corresponding indices.

There are two device name aliases:

default

Select the AVFoundation default device of the corresponding type.

none

Do not record the corresponding media type.
This is equivalent to specifying an empty device name or index.

If set to true, a list of all available input devices is given showing all
device names and indices.

-video_device_index <INDEX>

Specify the video device by its index. Overrides anything given in the input filename.

-audio_device_index <INDEX>

Specify the audio device by its index. Overrides anything given in the input filename.

-pixel_format <FORMAT>

Request the video device to use a specific pixel format.
If the specified format is not supported, a list of available formats is given
and the first one in this list is used instead. Available pixel formats are:
monob, rgb555be, rgb555le, rgb565be, rgb565le, rgb24, bgr24, 0rgb, bgr0, 0bgr, rgb0,
bgr48be, uyvy422, yuva444p, yuva444p16le, yuv444p, yuv422p16, yuv422p10, yuv444p10,
yuv420p, nv12, yuyv422, gray

-framerate

Set the grabbing frame rate. Default is ntsc, corresponding to a
frame rate of 30000/1001.

To enable this input device, you need the Blackmagic DeckLink SDK and you
need to configure with the appropriate --extra-cflags
and --extra-ldflags.
On Windows, you need to run the IDL files through widl.

DeckLink is very picky about the formats it supports. Pixel format of the
input can be set with raw_format.
Framerate and video size must be determined for your device with
-list_formats 1. Audio sample rate is always 48 kHz and the number
of channels can be 2, 8 or 16. Note that all audio channels are bundled in one single
audio track.

If set to true, print a list of devices and exit.
Defaults to false. Alternatively you can use the -sources
option of ffmpeg to list the available input devices.

list_formats

If set to true, print a list of supported formats and exit.
Defaults to false.

format_code <FourCC>

This sets the input video format to the format given by the FourCC. To see
the supported values of your device(s) use list_formats.
Note that there is a FourCC 'pal ' that can also be used
as pal (3 letters).
Default behavior is autodetection of the input video format, if the hardware
supports it.

bm_v210

This is a deprecated option, you can use raw_format instead.
If set to ‘1’, video is captured in 10 bit v210 instead
of uyvy422. Not all Blackmagic devices support this option.

raw_format

Set the pixel format of the captured video.
Available values are:

‘uyvy422’

‘yuv422p10’

‘argb’

‘bgra’

‘rgb10’

teletext_lines

If set to nonzero, an additional teletext stream will be captured from the
vertical ancillary data. Both SD PAL (576i) and HD (1080i or 1080p)
sources are supported. In case of HD sources, OP47 packets are decoded.

This option is a bitmask of the SD PAL VBI lines captured, specifically lines 6
to 22, and lines 318 to 335. Line 6 is the LSB in the mask. Selected lines
which do not contain teletext information will be ignored. You can use the
special all constant to select all possible lines, or
standard to skip lines 6, 318 and 319, which are not compatible with
all receivers.

For SD sources, ffmpeg needs to be compiled with --enable-libzvbi. For
HD sources, on older (pre-4K) DeckLink card models you have to capture in 10
bit mode.

channels

Defines number of audio channels to capture. Must be ‘2’, ‘8’ or ‘16’.
Defaults to ‘2’.

duplex_mode

Sets the decklink device duplex mode. Must be ‘unset’, ‘half’ or ‘full’.
Defaults to ‘unset’.

timecode_format

Timecode type to include in the frame and video stream metadata. Must be
‘none’, ‘rp188vitc’, ‘rp188vitc2’, ‘rp188ltc’,
‘rp188any’, ‘vitc’, ‘vitc2’, or ‘serial’. Defaults to
‘none’ (not included).

If set to ‘true’, color bars are drawn in the event of a signal loss.
Defaults to ‘true’.

queue_size

Sets maximum input buffer size in bytes. If the buffering reaches this value,
incoming frames will be dropped.
Defaults to ‘1073741824’.

audio_depth

Sets the audio sample bit depth. Must be ‘16’ or ‘32’.
Defaults to ‘16’.

decklink_copyts

If set to true, timestamps are forwarded as they are without removing
the initial offset.
Defaults to false.

timestamp_align

Capture start time alignment in seconds. If set to nonzero, input frames are
dropped till the system timestamp aligns with configured value.
Alignment difference of up to one frame duration is tolerated.
This is useful for maintaining input synchronization across N different
hardware devices deployed for ’N-way’ redundancy. The system time of different
hardware devices should be synchronized with protocols such as NTP or PTP,
before using this option.
Note that this method is not foolproof. In some border cases input
synchronization may not happen due to thread scheduling jitters in the OS.
Either sync could go wrong by 1 frame or in a rarer case
timestamp_align seconds.
Defaults to ‘0’.

Select video input pin number for crossbar device. This will be
routed to the crossbar device’s Video Decoder output pin.
Note that changing this value can affect future invocations
(sets a new default) until system reboot occurs.

crossbar_audio_input_pin_number

Select audio input pin number for crossbar device. This will be
routed to the crossbar device’s Audio Decoder output pin.
Note that changing this value can affect future invocations
(sets a new default) until system reboot occurs.

show_video_device_dialog

If set to true, before capture starts, popup a display dialog
to the end user, allowing them to change video filter properties
and configurations manually.
Note that for crossbar devices, adjusting values in this dialog
may be needed at times to toggle between PAL (25 fps) and NTSC (29.97)
input frame rates, sizes, interlacing, etc. Changing these values can
enable different scan rates/frame rates and avoiding green bars at
the bottom, flickering scan lines, etc.
Note that with some devices, changing these properties can also affect future
invocations (sets new defaults) until system reboot occurs.

show_audio_device_dialog

If set to true, before capture starts, popup a display dialog
to the end user, allowing them to change audio filter properties
and configurations manually.

show_video_crossbar_connection_dialog

If set to true, before capture starts, popup a display
dialog to the end user, allowing them to manually
modify crossbar pin routings, when it opens a video device.

show_audio_crossbar_connection_dialog

If set to true, before capture starts, popup a display
dialog to the end user, allowing them to manually
modify crossbar pin routings, when it opens an audio device.

show_analog_tv_tuner_dialog

If set to true, before capture starts, popup a display
dialog to the end user, allowing them to manually
modify TV channels and frequencies.

show_analog_tv_tuner_audio_dialog

If set to true, before capture starts, popup a display
dialog to the end user, allowing them to manually
modify TV audio (like mono vs. stereo, Language A,B or C).

audio_device_load

Load an audio capture filter device from file instead of searching
it by name. It may load additional parameters too, if the filter
supports the serialization of its properties to.
To use this an audio capture source has to be specified, but it can
be anything even fake one.

audio_device_save

Save the currently used audio capture filter device and its
parameters (if the filter supports it) to a file.
If a file with the same name exists it will be overwritten.

video_device_load

Load a video capture filter device from file instead of searching
it by name. It may load additional parameters too, if the filter
supports the serialization of its properties to.
To use this a video capture source has to be specified, but it can
be anything even fake one.

video_device_save

Save the currently used video capture filter device and its
parameters (if the filter supports it) to a file.
If a file with the same name exists it will be overwritten.

Set the video frame size. The default is to capture the full screen if desktop is selected, or the full window size if title=window_title is selected.

offset_x

When capturing a region with video_size, set the distance from the left edge of the screen or desktop.

Note that the offset calculation is from the top left corner of the primary monitor on Windows. If you have a monitor positioned to the left of your primary monitor, you will need to use a negative offset_x value to move the region to that monitor.

offset_y

When capturing a region with video_size, set the distance from the top edge of the screen or desktop.

Note that the offset calculation is from the top left corner of the primary monitor on Windows. If you have a monitor positioned above your primary monitor, you will need to use a negative offset_y value to move the region to that monitor.

To enable this input device, you need libiec61883, libraw1394 and
libavc1394 installed on your system. Use the configure option
--enable-libiec61883 to compile with the device enabled.

The iec61883 capture device supports capturing from a video device
connected via IEEE1394 (FireWire), using libiec61883 and the new Linux
FireWire stack (juju). This is the default DV/HDV input method in Linux
Kernel 2.6.37 and later, since the old FireWire stack was removed.

Specify the FireWire port to be used as input file, or "auto"
to choose the first port connected.

Override autodetection of DV/HDV. This should only be used if auto
detection does not work, or if usage of a different device type
should be prohibited. Treating a DV device as HDV (or vice versa) will
not work and result in undefined behavior.
The values auto, dv and hdv are supported.

dvbuffer

Set maximum size of buffer for incoming data, in frames. For DV, this
is an exact value. For HDV, it is not frame exact, since HDV does
not have a fixed frame size.

dvguid

Select the capture device by specifying its GUID. Capturing will only
be performed from the specified device and fails if no device with the
given GUID is found. This is useful to select the input if multiple
devices are connected at the same time.
Look at /sys/bus/firewire/devices to find out the GUIDs.

To enable this input device during configuration you need libjack
installed on your system.

A JACK input device creates one or more JACK writable clients, one for
each audio channel, with name client_name:input_N, where
client_name is the name provided by the application, and N
is a number which identifies the channel.
Each writable client will send the acquired data to the FFmpeg input
device.

Once you have created one or more JACK readable clients, you need to
connect them to one or more JACK writable clients.

To connect or disconnect JACK clients you can use the jack_connect
and jack_disconnect programs, or do it through a graphical interface,
for example with qjackctl.

To list the JACK clients and their properties you can invoke the command
jack_lsp.

Follows an example which shows how to capture a JACK readable client
with ffmpeg.

Format modifier to signal on output frames. This is necessary to import correctly into
some APIs, but can’t be autodetected. See the libdrm documentation for possible values.

crtc_id

KMS CRTC ID to define the capture source. The first active plane on the given CRTC
will be used.

plane_id

KMS plane ID to define the capture source. Defaults to the first active plane found if
neither crtc_id nor plane_id are specified.

framerate

Framerate to capture at. This is not synchronised to any page flipping or framebuffer
changes - it just defines the interval at which the framebuffer is sampled. Sampling
faster than the framebuffer update rate will generate independent frames with the same
content. Defaults to 30.

Capture from the first active plane, download the result to normal frames and encode.
This will only work if the framebuffer is both linear and mappable - if not, the result
may be scrambled or fail to download.

ffmpeg -f kmsgrab -i - -vf 'hwdownload,format=bgr0' output.mp4

Capture from CRTC ID 42 at 60fps, map the result to VAAPI, convert to NV12 and encode as H.264.

This input device reads data from the open output pads of a libavfilter
filtergraph.

For each filtergraph open output, the input device will create a
corresponding stream which is mapped to the generated output. Currently
only video data is supported. The filtergraph is specified through the
option graph.

Specify the filtergraph to use as input. Each video open output must be
labelled by a unique string of the form "outN", where N is a
number starting from 0 corresponding to the mapped input stream
generated by the device.
The first unlabelled output is automatically assigned to the "out0"
label, but all the others need to be specified explicitly.

The suffix "+subcc" can be appended to the output label to create an extra
stream with the closed captions packets attached to that output
(experimental; only for EIA-608 / CEA-708 for now).
The subcc streams are created after all the normal streams, in the order of
the corresponding stream.
For example, if there is "out19+subcc", "out7+subcc" and up to "out42", the
stream #43 is subcc for stream #7 and stream #44 is subcc for stream #19.

If not specified defaults to the filename specified for the input
device.

graph_file

Set the filename of the filtergraph to be read and sent to the other
filters. Syntax of the filtergraph is the same as the one specified by
the option graph.

The speed is specified CD-ROM speed units. The speed is set through
the libcdio cdio_cddap_speed_set function. On many CD-ROM
drives, specifying a value too large will result in using the fastest
speed.

paranoia_mode

Set paranoia recovery mode flags. It accepts one of the following values:

‘disable’

‘verify’

‘overlap’

‘neverskip’

‘full’

Default value is ‘disable’.

For more information about the available recovery modes, consult the
paranoia project documentation.

The OpenAL input device provides audio capture on all systems with a
working OpenAL 1.1 implementation.

To enable this input device during configuration, you need OpenAL
headers and libraries installed on your system, and need to configure
FFmpeg with --enable-openal.

OpenAL headers and libraries should be provided as part of your OpenAL
implementation, or as an additional download (an SDK). Depending on your
installation you may need to specify additional flags via the
--extra-cflags and --extra-ldflags for allowing the build
system to locate the OpenAL headers and libraries.

An incomplete list of OpenAL implementations follows:

Creative

The official Windows implementation, providing hardware acceleration
with supported devices and software fallback.
See http://openal.org/.

OpenAL Soft

Portable, open source (LGPL) software implementation. Includes
backends for the most common sound APIs on the Windows, Linux,
Solaris, and BSD operating systems.
See http://kcat.strangesoft.net/openal.html.

This device allows one to capture from an audio input device handled
through OpenAL.

You need to specify the name of the device to capture in the provided
filename. If the empty string is provided, the device will
automatically select the default device. You can get the list of the
supported devices by using the option list_devices.

If FFmpeg is built with v4l-utils support (by using the
--enable-libv4l2 configure option), it is possible to use it with the
-use_libv4l2 input device option.

The name of the device to grab is a file device node, usually Linux
systems tend to automatically create such nodes when the device
(e.g. an USB webcam) is plugged into the system, and has a name of the
kind /dev/videoN, where N is a number associated to
the device.

Video4Linux2 devices usually support a limited set of
widthxheight sizes and frame rates. You can check which are
supported using -list_formats all for Video4Linux2 devices.
Some devices, like TV cards, support one or more standards. It is possible
to list all the supported standards using -list_standards all.

The time base for the timestamps is 1 microsecond. Depending on the kernel
version and configuration, the timestamps may be derived from the real time
clock (origin at the Unix Epoch) or the monotonic clock (origin usually at
boot time, unaffected by NTP or manual changes to the clock). The
-timestamps abs or -ts abs option can be used to force
conversion into the real time clock.

Some usage examples of the video4linux2 device with ffmpeg
and ffplay:

List supported formats for a video4linux2 device:

ffplay -f video4linux2 -list_formats all /dev/video0

Grab and show the input of a video4linux2 device:

ffplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0

Grab and record the input of a video4linux2 device, leave the
frame rate and size as previously set:

To enable this input device during configuration you need libxcb
installed on your system. It will be automatically detected during
configuration.

This device allows one to capture a region of an X11 display.

The filename passed as input has the syntax:

[hostname]:display_number.screen_number[+x_offset,y_offset]

hostname:display_number.screen_number specifies the
X11 display name of the screen to grab from. hostname can be
omitted, and defaults to "localhost". The environment variable
DISPLAY contains the default display name.

x_offset and y_offset specify the offsets of the grabbed
area with respect to the top-left border of the X11 screen. They
default to 0.

Specify whether to draw the mouse pointer. A value of 0 specifies
not to draw the pointer. Default value is 1.

follow_mouse

Make the grabbed area follow the mouse. The argument can be
centered or a number of pixels PIXELS.

When it is specified with "centered", the grabbing region follows the mouse
pointer and keeps the pointer at the center of region; otherwise, the region
follows only when the mouse pointer reaches within PIXELS (greater than
zero) to the edge of region.

Set the grabbing region coordinates. They are expressed as offset from
the top left corner of the X11 window and correspond to the
x_offset and y_offset parameters in the device name. The
default value for both options is 0.

Output devices are configured elements in FFmpeg that can write
multimedia data to an output device attached to your system.

When you configure your FFmpeg build, all the supported output devices
are enabled by default. You can list all available ones using the
configure option "–list-outdevs".

You can disable all the output devices using the configure option
"–disable-outdevs", and selectively enable an output device using the
option "–enable-outdev=OUTDEV", or you can disable a particular
input device using the option "–disable-outdev=OUTDEV".

The option "-devices" of the ff* tools will display the list of
enabled output devices.

To enable this output device, you need the Blackmagic DeckLink SDK and you
need to configure with the appropriate --extra-cflags
and --extra-ldflags.
On Windows, you need to run the IDL files through widl.

DeckLink is very picky about the formats it supports. Pixel format is always
uyvy422, framerate, field order and video size must be determined for your
device with -list_formats 1. Audio sample rate is always 48 kHz.

Disables default SDL window when set to non-zero value.
Application must provide OpenGL context and both window_size_cb and window_swap_buffers_cb callbacks when set.

window_title

Set the SDL window title, if not specified default to the filename specified for the output device.
Ignored when no_window is set.

window_size

Set preferred window size, can be a string of the form widthxheight or a video size abbreviation.
If not specified it defaults to the size of the input video, downscaled according to the aspect ratio.
Mostly usable when no_window is not set.

When both options are provided then the highest value is used
(duration is recalculated to bytes using stream parameters). If they
are set to 0 (which is default), the device will use the default
PulseAudio duration value. By default PulseAudio set buffer duration
to around 2 seconds.

prebuf

Specify pre-buffering size in bytes. The server does not start with
playback before at least prebuf bytes are available in the
buffer. By default this option is initialized to the same value as
buffer_size or buffer_duration (whichever is bigger).

minreq

Specify minimum request size in bytes. The server does not request less
than minreq bytes from the client, instead waits until the buffer
is free enough to request more bytes at once. It is recommended to not set
this option, which will initialize this to a value that is deemed sensible
by the server.

Specify the hardware display name, which determines the display and
communications domain to be used.

The display name or DISPLAY environment variable can be a string in
the format hostname[:number[.screen_number]].

hostname specifies the name of the host machine on which the
display is physically attached. number specifies the number of
the display server on that host machine. screen_number specifies
the screen to be used on that server.

If unspecified, it defaults to the value of the DISPLAY environment
variable.

For example, dual-headed:0.1 would specify screen 1 of display
0 on the machine named “dual-headed”.

Check the X11 specification for more detailed information about the
display name format.

window_id

When set to non-zero value then device doesn’t create new window,
but uses existing one with provided window_id. By default
this options is set to zero and device creates its own window.

window_size

Set the created window size, can be a string of the form
widthxheight or a video size abbreviation. If not
specified it defaults to the size of the input video.
Ignored when window_id is set.

window_x

window_y

Set the X and Y window offsets for the created window. They are both
set to 0 by default. The values may be ignored by the window manager.
Ignored when window_id is set.

window_title

Set the window title, if not specified default to the filename
specified for the output device. Ignored when window_id is set.

For details about the authorship, see the Git history of the project
(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
git log in the FFmpeg source directory, or browsing the
online repository at http://source.ffmpeg.org.

Maintainers for the specific components are listed in the file
MAINTAINERS in the source code tree.